1. Field of the Invention
The present invention relates to a round, multi-layer flexible plastic bottle that is suitable for the packaging of an oxygen-sensitive, hot-fill product such as a comestible juice product, and the present invention further relates to a package that includes such a bottle with the packaged product contained therein and with a closure and label applied thereto.
2. Description of the Prior Art
Over the course of the past several years, blown plastic bottles have replaced glass bottles and metal cans as the preferred package for packaging many products, including many liquid products. This trend has developed and continued due to the many costs and handling advantages which plastic bottles have relative to glass bottles and metal cans. Until recently however, one of the characteristics of blown plastic bottles that has limited its suitability for many packaging applications was the fact that the available plastic materials were susceptible to oxygen migration through the plastic material. Many food products tend to degrade when exposed to oxygen over prolonged periods of time and, thus, until recently, such food products could not be packaged satisfactorily in blown plastic bottles.
In more recent times, technology has developed which permits the production of blown plastic bottles from a co-extruded material that includes a multiplicity of layers of various of organic materials, and in this so-called multi-layer plastic packaging technology, it is possible to include a layer of an organic material that serves as an effective barrier to the transmission of oxygen, such as ethylene vinyl alcohol, or polyvinyledene chloride. Such barrier materials tend to be quite expensive, but through the multi-layer technology, the use of such a barrier material is economically feasible for many packaging applications because the barrier layer can be quite thin, other layers of the multi-layer bottle construction of a less expensive nature being utilized to impart virtually all of the needed structural strength of the finished product. Thus, multi-layer plastic bottles that include an oxygen barrier layer are now in use in the packaging of oxygen-sensitive food products, such as catsup and barbecue sauces.
Another of the characteristics of a plastic bottle relative to a glass bottle or a metal can is the flexibility or the lack of rigidity of the plastic bottle, and this characteristic is shared by blown plastic multi-layer bottles. This characteristic is especially pronounced in the packaging of products that tend to change in volume after the filling and closing of the bottle, such as hot-fill food products that tend to shrink in volume due to thermal contraction after the capping of the filled bottle while the contents are still hot. Other products tend to change in volume due to the volatile or gas absorbing nature of the packaged product, as is explained in U.S. Pat. No. 4,387,816 (R. L. Weckman), which is assigned to the assignee of this application.
The tendency for certain packaged products to change in volume after packaging and capping, as described above, tends to change the shape of a plastic bottle because of the inherent flexibility of known types of plastic bottles, including multi-layer plastic bottles, and this is a problem which is new to the use of plastic bottles for these packaging applications, glass bottles and metal cans having sufficient inherent rigidity to resist the forces resulting from such a change in the volume of the package without a material degree of distortion of the shape of the glass bottle or metal can, as the case may be.
Many plastic bottle designs have been proposed in an effort to deal with the problem of the distortion of the shape of a plastic bottle due to a change in the volume of the packaged product, but such designs tend to involve the use of oval or flat-panel or other non-round bottles, such as that described in the aforesaid U.S. Pat. No. 4,387,816. Thus, for example, multi-layer plastic bottles for the packaging of catsup are generally oval in shape, notwithstanding that prior art glass catsup bottles were round or polygonol in shape. Insofar as the packaging of catsup is concerned, the use of a non-round or non-polygonal bottle has proved to be advantageous, because an oval bottle can be more readily squeezed than a round or square bottle, and such squeezability assists in the withdrawal of the catsup due to its viscous nature.
Certain hot-fill comestible liquid products, however, such as tomato juice and citrus juices, can be readily withdrawn from a multi-layer plastic bottle without squeezing, and the use of a non-round bottle for the packaging of any such product, therefore, offers no particular functional advantage. In fact, such products have traditionally been packaged in glass bottles of a round shape, and the round bottle shape is now associated with such juice products and offers certain marketing advantages in connection with the packaging of such juice products. In addition, round bottles can be more readily processed on existing filling lines that were installed for the filling of cans or glass bottles, as round bottles need not be oriented in the circumferential direction in any particular manner as they travel through any such filling line, thus reducing the capital costs involved in adapting any such existing filling line to the handling of plastic bottles. However, it has not been heretofore possible to package such hot-fill juice products in round, multi-layer plastic bottles because of the distortion in shape experienced by the bottle as the volume of the juice contracts as a result of the cooling of the juice from the fill temperature, typically at least approximately 190.degree. F., after the capping of the bottle, a step which normally occurs immediately after filling. This distortion is particularly severe in the case of a bottle that utilizes a generally cylindrical main body portion, since it tends to occur at the middle of the cylindrical main body portion, producing an hourglass configuration. This a problem which complicates the application of a double-ended or wraparound label to the bottle, since such a label is normally applied to the cylindrical main body portion of a round bottle, and the effect is particularly pronounced in the large bottles, e.g., typically 48 fl. oz. and 64 fl. oz (or 1.5 liters and 2.0 liters) that are popular in the packaging of hot-fill juice products.